html {
  font-family: Arial, Helvetica, sans-serif;
  font-size: 14pt;
  line-height: 1.3;
}

body {
  width: 800px;
  max-width: 90%;
  margin: 5rem auto;
}

article {
  margin: 5rem 0;
}

section {
  margin: 3rem 0;
}

h1, h2, h3, h4, h5, h6 {
  font-weight: normal;
}

article > h1 {
  font-weight: bold;
}

samp {
  display: block;
  margin: 1em 0;
}

code, kbd {
  color: steelblue;
  font-style: normal;
  font-weight: normal;
}

code.tag::before {
  content: "<";
}

code.tag::after {
  content: ">";
}

ol.instructions {
  background-color: #f2f2f2;
  padding: 1rem 1rem 1rem 2rem;
  color: #666666;
  font-style: italic;
  font-size: 0.8rem;
  line-height: 1.2;
}

ol.instructions > li {
  margin: 0.4rem 0;
}

ol.instructions > li:first-child { margin-top: 0; }
ol.instructions > li:last-child { margin-bottom: 0; }

aside {
  padding: 1rem 2rem;
  color: white;
  background-color: gray;
  font-size: 0.8rem;
  margin: 1em 0;
}

.overflow-example {
  padding: 1rem;
  border: 1px solid gray;
}

.portrait {
  width: 125px;
}

.positioned-element {
  width: 50px;
  height: 50px;
  background-color: #ccc;
}

.static-example,
.relative-example,
.absolute-example,
.fixed-example,
.sticky-example {
  border: 1px solid #999;
  padding: 0 1rem;
}

.grid img {
    width: 150px;
    padding:0;
    width: 90%;
}

.grid li {
    display:block;
    width: 25%;
    text-align: center;
    font-size: 0.8rem;
    margin-bottom: 1rem;
}

.using-inline-block li {
    display: inline-block;
}

.using-inline-block {
    font-size: 0;
}

.using-flex {
    display:flex;
    flex-wrap:wrap;
}

.using-grid ul {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr 1fr;
}

using-grid li {
    width: 100%;
}